Apparatus for securing nails on plates made from pliable material, especially plywood plates



May 13, 1958 H. F. w. STEDLER 2,834,016

APPARATUS FOR SECURING NAILS ON PLATES MADE FROM PLIABLE MATERIAL, ESPECIALLY PLYWOOD PLATES Filed Dec. 7, 1955 4 Sheets-Sheet 1 //v vzNron:

H F W STedZer Byvm/ ATTYS.

F. w. STEDLER H. 2,834,016 APPARATUS FOR SECURING NAILS 0N PLATES MADE FROM May 13, 1958 PLIABLE MATERIAL, ESPECIALLY .PLYWOOD PLATES 4 Sheets-Sheet 2 Filed Dec. 7, 1955 /N YEA/TOR "HF If Sterile?"- y 3, 1958 H. F. w. STEDLER 2,834,016

APPARATUS FOR SECURING NAILS 0N PLATES MADE FROM FLIABLE MATERIAL. ESPECIALLY PLYWOOD PLATES Filed Dec. 7, 1955 4 Sheets-Sheet 3 HF V 1521962 187" ATTYS.

INVENTO/Q y 3, 1958 H. F. w. STEDLER 2,834,016

APPARATUS FOR SECURING NAILS ON PLATES MADE FROM PLIABLE MATERIAL, ESPECIALLY PLYWOOD PLATES 55 4 Sheets-Sheet 4 Filed Dec. 7, l9

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APPARATUS FGR SECURING NAILS ON PLATES MADE FROM PLIABLE MATERIAL, ESPECIALLY PLYWOOD PLATES Heinrich Friedrich Wilhelm Stedler, Lauterbach, Hessen,

Germany, assignor to Durabel-Faltbox Stedler Kornmanditgesellschaft, Lauterbach, Hessen, Germany Application December 7, 1955, Serial No. 551,695 Claims priority, application Germany December 20, 1954 8 Claims. (Cl. 11)

recess in which said resiliently mounted sleeve is sunk, t

a locking member firmly holding said table-plate while tates Patent a the nail is being driven in, and means for disengaging said locking member after the nail has been driven right home to allow said table-plate to descend on to the clinching-anvil to bend the nail point and guide the pro- Fig. 1 is a front elevational view, partly in section,

of a machine for carrying out the method according to the invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is a vertical section on a larger scale showing the parts of the machine which are essentialfor carrying out the method;

Fig. 4 is a part vertical cross section taken on line IV-IV of Fig. 3;

Fig. 5 is a vertical cross section of a hole piercing sleeve;

Fig. 6 is a side elevational view of a holding and guiding sleeve;

Fig. 7 is a vertical cross section on line VII -VII of Fig. 6;

Figs. 8 and 9 show a two-armed retaining and center ing blade spring fitted on each nail holding and guiding sleeve, Fig. 8 being a section taken along line VlII-VIII of Fig. 9 and Fig. 9 being a front elevational view thereof;

Figs. 10 and 11 show the upper part of a pin-like clinching-anvil or dolly in two side elevations turned through an angle of 90 and on a considerably enlarged scale as compared with Fig. 3;

Fig. 12 is a cross-section through the hole piercing sleeve pushed out into its extreme working position with the aid of a nailing hammer;

Fig. 13 is a cross section through the nail holding and guiding sleeve with a nail inserted therein;

Fig. 14 is a cross section through the nail holding and guiding sleeve in the position in which the nail has been driven to the bottom of a pierced hole by the nailing hammer;

Fig. 15 is a cross section corresponding to that shown inFig. 14 with the nail driven home in the workpiece; Fig.16 is a simplified diagrammatic view showing a 2,834,016 Patented May 13, 1958 2 spiral winding operation performed on the end of the nail shank projecting downwards beyond the workpiece;

Figs. 17 and 18 are diagrammatic views of the finished, shaped and flat-pressed spiral seen from two different positions;

Fig. 19 is a side elevation of the flattened spiral;

Fig. 20 is a cross section similar to that of Fig. 3 showing the lower part of the machine when the upper part of the machine has descended into its extreme position and the table plate under the pressure of the upper part of the machine has moved downward out of its normal position;

Fig. 21 shows the'left side of the nailing machine, partly in elevation and partly in vertical longitudinal section;

Fig. 22 is a horizontal cross section vtaken on line XXIIXXII of Fig. 21 with the table plate partly broken away; and

Fig. 23 is a side elevation of the nailing machine, in vertical section.

The method for connecting plates of pliable material, embodied in this invention, is carried out by means of an apparatus which is constructed, as shown in Figs. 1, 2, and 3, like an eccentric press and consists substantially of four uprights 2 vertically slidable relatively to a base 1 and on the upper ends of which a cross-head 3 is bolted. The drive of the verticallymovable cross-head 3 with the four uprights 2 is effected by means of an electric motor, not shown in the drawings, or some other suitable driving arrangement, through the intermediary. of a shaft 4 carryingeccentric disks 5 and rotatably mounted in the machine base 1. The driving power is transmitted by rings 6 rotatable on the eccentric disks 5 and provided with bore-s for the engagement of pins 7. These pins are mounted on cross-members 8 which are each bolted on the lower ends of two of the uprights 2 on the same side of the machine. Each of the four uprights is slidably guidedboth in the lower and also in. the upper part of the machine base 1. The upper part of the base 1 is constructed as a working table 1 on which the lower part of the nailing machine is mounted.

The cross-head 3 is provided with a beam-like extension 3 to which a vertically shiftable pressure beam 9 is detachably connected by bolts 10 (see Figs. 21 and 23) and has a. dove-tail extension 9 .fitting in a similarly shaped recess in the cross-head extension 3 A plate 11 is-fitted on the underside of the pressure beam 9 on which plate a plurality of pin-like nailing hammers 12, each of which has a comically widening upper end, is rigidly secured; in that the conically widening ends bear against the underside of the pressure beam9. A second beam 13 is-arranged below and in spaced relation to the pressure partly beam 9; The beam 13 is shifitable in vertical direction 'These bolts have widened heads insertable in. bores 16 inthe beam1 3. The bolts 14 serve both to guide the vertical movements-of beam 13 and as a means for securing the plate 11- on the underside of the pressure beam 9. The bolts 14, in turn are; fixed on the pressure beam 9 by screws 15 which are countersunk in bores inthe upper sideof the pressure beam 9 and in turn are screwed into threaded-holes inthe upper ends of the'bolts 14. When the machine is at. rest the beam 13 is-held spaced from the pressurebea-m 9 by spiral springs 17, the upper ends of-which are secured in holes in the plate 1.1 whereas their lowerends engage in suitable bores in the beam 13. Bores 18 are also formed int'he beam 13 for the pin-like nailing hammers 12 arranged at uniform distances; apart. Thelowerends, of the nailing hammers 12 completely recede into bores 1 8'whenin position of rest, ascanbe seen fromFig. 21. v

A transversely; movable 1,swing beam 19 is mountedun der the beam 13. Beam 19 is in direct contact with beam 13 and is resiliently pressed against it. cam 19 serves as a carrier for the vertically slidable piercing sleeves 28 and nail holding and guiding sleeves 33. The swing beam 19 is held on one side by springs 20 which are anchored on angle-pieces 21, 22 on the beams 13 and 19, respectively. On the other side, the rear side of the machine, a link guiding system is provided. This guiding system includes links 23 which are each pivotally connected to two angle-pieces 24, and 25, of which the angle-pieces 24 are fixed on the beam 33 and the angle-pieces 25 on the swing beam 19. Thus it is possible to move the swing beam 19 out of the position shown in Fig. 3 a distance y towards the left without longitudinal displacement, the links 23 thereby turning through an angle to about the extent of the are or curve 2: indicated in Fig. 3.

The swing beam 19 has two rows of holes 26 and 27 arranged one behind the other and spaced to correspond with the nailing hammers 12. The holes 26 in the front row, shown on the left-hand side in Fig. 3, serve for the reception and guiding of the vertically slidable piercing sleeves 28 whereas the holes 27 of the rear row accommodate the nail holding and guiding sleeves 33 which are not vertically shiftable.

Each of the piercing sleeves 28 (see Figs. 3 and 5) consists of a cylindrical hollow body with a closed lower end below an axial bore 30, which closed lower end is shaped to a point 29 merging from a wide angle cone into a sharp angle cone. At its upper end the axial bore 39 of each piercing sleeve 28 is conically widened to allow free passage of the nailing hammer 12 coordinated to it. The remaining portions of the axial bores 30 conform to the external diameter of the nailing hammers 12. The vertically shiftable piercing sleeves 28 are yieldably mounted on spiral springs 31 which bear against a collar at the top of the sleeve and against a shoulder in the bore 26 at the bottom. When at rest, the vertically shiftable piercing sleeves 28 are in the position shown in Fig. 3. At this time their upper end faces are in contact with a holding plate 32 fitted in a recess in the upper side of the swing beam 19 and their points 29 are located within the bores 26.

The nail holding and guiding sleeves 33 are cylindrical bodies with a continuous axial bore 34 which is of the same diameter as the bore 3% in the piercing sleeves 28 and, like the bore 30, widens conically at the upper mouth. Owing to the fact that a short cylindrical extension 33 of smaller diameter at the lower end of the sleeve 33 engages in a section of the bore 27 of reduced diameter, the exact central position of each sleeve 33 in its bore 27 is ensured. At two diametrically opposite points the sleeve 33 is provided with longitudinal grooves 33 in which two two-armed blade springs 35 are accommodated. The two arms of the blade springs 35 are of different length and the free ends of the longer arms are located in front of the lower mouth of the axial bore 34 and thus prevent a nail a introduced into the nail sleeve from dropping out prematurely. Furthermore, the blade springs 35 serve for centering the nail in the bore of the nail sleeve 33 as the edges of their inner arms are slightly rounded (see Fig. 8). The nails are guided by these rounded portions when being driven into a workpiece b, so that the nail cannot assume a crooked position in the axial bore 34 as it passes vertically through the workpiece when driven by the nailing hammer. An annular groove 36 arranged near the upper end of the sleeve 33 in the outer wall thereof accommodates the rounded apices of the two-armed blade springs 35 and locks these in position after the sleeves 33 have been fitted in the bores 27 in the swing beam 19. The above mentioned holding plate 32 secures not only the vertically slidable piercing sleeves 28 but also the nail holding and guiding sleeves 33 in the proper fitted position.

On the rear side of the nailing machine a nail feed- 4 ing arrangement 37 is provided which can be charged with nails either by hand or automatically and from which the nails are conducted to the sleeves 33 through channels 33 when the swing beam 19 is in the swung-back position shown in Fig. 3.

Two vertical square-section rods 39 are mounted on the lower part of the nailing machine for guiding the vertically shiftable pressure beam 9. Rollers 40 are secured to the pressure beam 9 which run upwards and downwards on the outer surfaces of these rods 39 while .ic rs 41 of the pressure beam 9 slide up and down on the side surfaces thereof when the machine is in operation. The beam 13 can also be advantageously guided on the side surfaces of the square rods 39 by means of guide-members 42. A support 4-3 for rollers is also connected to the guide-members 42, which rollers $4 control the downward movement of a table plate 51 in cooperation with an arrangement of the lower part of the nailing machine, which will be hereinafter described.

The lower part of the nailing machine consists of a lower housing body 45 mounted on the working table 1 of the machine, an upper housing body 46 and a plate 47 arranged between the two housing bodies and serving as partition wall for an endless pulling element 80 of a rope or belt drive by means of which rope or belt pulleys of each two neighbouring elements, arranged at different levels, are driven in a manner to be hereinafter described. Overhanging arms 48 are bolted on to the rear side of the upper housing body 46. At the free ends of these arms which are constructed as solid journal bearings 49 carrier arms 50 are pivotally mounted and carry the table plate 51 extending across the entire width of the machine. Below the forward portion of the table plate 51 a spline shaft 52 is provided. This spline shaft 52, extending in a recess 53 in the upper housing body 46, normally rigidly supports the forward portion of the table plate 51 and is rotatably mounted in two bearings 54, formed by the upper housing body as, by means of square trunnions 55 projecting from the end faces of the spline shaft 52 up to points which lie beyond the two bearings 54. Cams 56 are mounted on these square trunnions 55, which cams 55 have upper and lower end portions. The upper end portions of the cams 56 are constructed as cam surfaces 57 for the rollers 44 of the upper part of the nailing machine.

Tension springs 53 engage the lower end portions of the cams 56 constructed like levers and tend to maintain the cams, and with them the rotary spline shaft 52, in the position shown in Fig. 3, in which the rotary spline shaft 52 looks the table plate 51 against swinging in downward direction, and turn the rotary spline shaft 52 back into its initial position after the table plate 51 has again been raised. Pressure springs 61 are inserted in bores 62 provided in the upper housing body 46 and in bores 59 provided in the table plate 51 for again swinging up the table plate. These springs 61 press the table plate 51 back into its initial position shown in Fig. 3 as soon as the pressure exerted by the lowered upper part of the nailing machine ceases to act and the upper part of the machine is returned into its initial position.

The swinging range of the table plate 51 is limited by hinge leaves 62 fitted on the front edge of the table plate and provided with slots 63 by means of which they are guided on the shanks of cylindrical headed screws 64 which are screwed in to the front of the upper housing body 46. A second hinge 65 on the front edge of the table plate 51 serves for connecting a supporting plate 66, indicated in Fig. 22, on which supporting plate 66 the workpiece is fed to the nailing machine and which must be able to follow the downward movement of the table plate 51 at least at the point of connection.

As can be seen from Figs. 3 and 23, the rotary spline shaft 52 is so arranged in relation to the cam surface 57 of the cam 56 that the turning of the rotary spline shaft 52 through a small angle of about 30 will sufiice to'turn the spline shaft so far that the rigid support of the table plate 51 is release-l thereby and as the table plate is depressed further this in turn turns the spline shaft 52 until the table plate 51 reaches its extreme lower position determined by the slots 63 and screws 64.

The table plate 51 has apertures 67 at the points opposite the vertically shiftable piercing sleeves 28 or, when the pressure beam 9 is pulled forward, opposite the nail guiding and holding sleeves 33. Below these apertures 67 counter-tools for the piercing sleeves 28 and the sleeves 33 are fitted in the two housing bodies 45, 46 of the lower part of the nailing machine. Each of these counter-tools consists of an upper or clinching anvil structure comprising an anvil sleeve 69 resiliently supported by a spiral spring 68 and vertically shiftable relatively to a lower sleeve 70 but coupled to this sleeve 70 by a cross pin 71 so as to be rotatable therewith. Vertical slots 72 are formed in the wall of the anvil sleeve 69 for the engagement of the cross pin 71. The lower sleeve 70 has a lower end of reduced diameter by means of which it is rotatable in a bore in the lower housing body 45. A plate 73 is fitted in a recess formed in the underside of the lower housing body 45 and extends over the entire length thereof forming a bearing for the sleeves 70 and covering all the sleeves at their lower ends.

As shown in Fig. 4, a bolt 74 is screwed into a screwthreaded bore in the bottom part of the lower sleeve 70 and extends into a widened portion of the axial bore in the anvil sleeve 69. This bolt 74 serves as carrier and support for a pin-like clinching anvil 75 which is detachably connected to the bolt 74 by another screw connection. The clinching anvil 75, which is not vertically shiftable, is rotatably guided at its upper end in the narrow upper portion of a bore '76 in the anvil sleeve 69. The end face of the clinching anvil 75, located within the bore 76 (see Figs. and ll), is provided with claw-like inclined surfaces 77 which serve for engaging the point of the nail driven through the workpiece and for shaping the projecting end of the nail shaft in the bore 76 into the form of a spiral which is pressed tightly against the underside of the workpiece under the action of the nailing hammer 12 and the counter pressure of the clinching anvil '75 serving somewhat like an anvil.

The anvil sleeve 69 is rotated at a high speed during the nailing operation by means of a rope or belt drive through the intermediary of the lower sleeve 7%) on which it is guided. Each lower sleeve 76 is provided with a rope or belt pulley 78 for this purpose. For constructional reasons and in order to prevent sections of the endless pulling element 80 running over all the guide pulleys 78 and corresponding reversing pulleys 79 (see Fig. 2) for touching each other between the pulleys, the

rope or belt pulleys 73 of each two neighbouring lower sleeves 7d are arranged at difierent levels (see Fig. 3) and in addition the above mentioned separating or partition plate 47 is provided.

The endless pulling element 89 is driven by an electric motor 81 through the intermediary of a shaft 82 rotatable in bearings 83 which are mounted on angle brackets 84 on the rear side of the working table 1 The shaft 82 carries the reversing pulleys 79. The electric motor 81 can be mounted on one of the angle brackets 84 (see Fig. 2). The speed of rotation of the rope or belt pulleys 78 and of the anvil sleeves 69 is so chosen that the peripheral speed of the pin-like clinching anvils 75 is greater than the striking speed of the nailing hammer 12.

In order to prevent Wood chips and foreign bodies from penetrating the bearings of the rotating anvil sleeves 69, 70 annular plates 85, projecting freely in upward direction, are fitted on the head ends of the anvil sleeves 69 which are widened in collar-shape.

The nails a are driven into the workpiece b and the 6 projecting ends of the nail shanks are subsequently clinched or secured in the following manner:

The workpiece b or the parts thereof to be connected are placed ready for nailing preferably in a template on the supporting plate 66 and pushed with the template over the table plate 51 of the nailing machine under the upper part thereof. In the first working operation after the driving motor or the driving mechanism has been engaged, the piercing sleeves 28 come into operation. The upper part 2, 3, 9, 13, and 19 of the machine is moved downwards by the eccentric disks 5 and rings 6. During this movement the nailing hammers 12 press the piercing sleeves 28 so far downwards, against the force exerted by the spiral springs 31 holdingthem in inoperative position in the holes 26 in the swing beam 19, that points 29 of the piercing sleeves 28 penetrate the workpiece b and pierce conical holes therein. When the piercing sleeves 28 have about reached the piercing posi tion shown in Fig. 12, the rollers 44 and the earns 56 will release the rigidly held table plate 51 by turning the rotary spline shaft 52. Because of the pressure exerted by the upper part of the nailing machine as it continues its downward movement during which the pressure beam 9 approaches the beam 13, thereby compressing the spiral springs 17, the table plate 51 is pressed into its lowermost position by the. swing beam 19 coming into contact with the workpiece b. During this movement the descending table plate 51 turns the rotary spline shaft 52 against the force exerted by the springs 58 beyond the position produced by the rollers 44 running on to the cams 56. When the eccentric disks 5 have exceeded their deadcenter position the upper machine part 2, 3, 9, 13, and 19 returns upwards into its initial position, whereby the spiral springs 17, in again relaxing, move the pressure beam 9 to the original distance from the nailing hammer guiding beam 13. The first working operation is terminated upon the completion of a full rotation of the eccentric disks 5. V

In the meantime a nail of exactly the right length has been introduced into each individual nail holding and guiding sleeve 33 through the channels 33. it is recommended that nails be used which are somewhat soft and do not offer too great a resistance to the bending deformation of the projecting ends of the shanks. The nail shanks may be of round or square or even polygonal cross section. The use of square nails presents certain advantages for bending into spiral shape the projecting ends of the nail shanks as angular section nails can turn less easily in the nail holes.

The blade springs 35 hold each nail in the axial bore 34 of the holding and guiding nail sleeves 33 in accurately centered position (see Fig. 13). Owing to the conical shape of the holes pierced in the workpiece the nails are additionally centered when being driven into the workpiece b (see Fig. 14). Thus, owing to the double centering, there is no danger of the nails becoming buckled or crooked when they are being driven through the workpiece, in spite of the softness of the nails.

Before commencing the second working operation the swing beam 19, which for this purpose is provided with a handle not shown in the drawings, is pulled forward so that the nail holding and guiding sleeves 33 will come under the nailing hammers 12. When the electric motor or the driving mechanism is again switched on, the upper part 2, 3, 9, 13, and 19 of the machine is moved downwards a second time and the nails a are then knocked out of the nail holding and guiding sleeves 33 and driven through the workpiece b. At the same time the drive for the anvil sleeves 69 is automatically engaged. The

moment the nail heads a, bear against the upper surface of the workpiece and the nail points are directly in front of the end faces of the clinching anvils 75 or the inclined surfaces 77 thereof (see Fig. 15) the rigid support of the table plate 51 is removed by the rotary spline shaft 52 in the manner described in connection with the piercing operation so that the table plate 51 can be swung downwards within the predetermined range of movement by the descending upper part of the machine.

As the table plate 51 swings downwards the anvil sleeves 69, as in the case of the piercing operation, are pushed downwards against the action of the spiral springs 68. During this movement the point of each nail is engaged by the inclined surfaces 77 of its clinching anvil 75, which does not shift vertically, is bent round sideways and, owing to the rapid rotation of the clinching-anvil, is formed into a spiral in the bore 76 of the anvil sleeve 6 and this spiral is pressed flat against the underside of the workpiece as the anvil sleeve 69 continues to descend and forms a flat-pressed spiral head The flat-pressed spiral head (1 formed into a disk in this manner eflects, in conjunction with the nail head a an extremely firm connection of the workpiece parts b joined by nailing. It is evident that the impact elfect and the feed speed of the nailing hammers 12 must be set according to the thickness of the workpiece so that the spiral is pressed tightly against the underside of the workpiece in the desired manner or even pressed slightly into the underside of the workpiece. The drive for imparting rotary motion to the anvil sleeves 69 can be again switched oil automatically during the return upward movement of the upper part of the nailing machine.

While the form of apparatus for carrying this method into effect constitutes the preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

I claim:

1. In an apparatus of the type described for nailing a plurality of superposed workpieces together, the combination of table means including a plate for supporting said workpieces, hammer means for driving a nail through said workpieces, clinching anvil means disposed below said table means and in alignment with said hammer means for engaging the protruding end of a nail shank after the nail is driven through the work ieces by said hammer means, resiliently mounted sleeve means surrounding said clinching anvil means, said piate being provided with a recess in which said resiliently mounted sleeve is sunk, said plate also being spring-biased, a locking member firmly holding said plate, while the nail is driven through said workpieces by said hammer means, means for disengaging said locking member after the nail is driven through said workpieces so as to allow said plate in said table means to descend and the protruding portion of the nail shank to contact said clinching anvil means, and means for rotating said anvil means whereby the protruding portion of the nail shank will be spirally twisted and pressed flat against a face of one of the workpieces.

2. The device as set forth in claim 1, wherein said clinching anvil has on its working surface a pair of projections inclined toward one side for engaging and twisting said protruding portion of the nail shank.

3. The device as set forth in claim 1, including means for rotating said clinching anvil so that the peripheral speed of the rotating anvil sleeve, measured at a point of the wall of the central bore of said sleeve is in excess of the feed speed of the hammer means driving the nail through said workpieces.

4. in an apparatus of the type described for nailing a plurality of superposed workpieces together, the combination of table means for supporting said workpieces, a nailing hammer suspended over said workpieces and said table means, suspension means for said nailing hammer, said suspension means including a resiliently mounted pressure beam, a swing beam disposed below said pressure beam intermediate said hammer and the workpieces, said swing beam being provided on one thereof with piercing means for forming a nail gr, hole in at least one of the workpieces, a nailholding sleeve mounted on the other side of said swing beam and in horizontal alignment with said piercing means, means operable in unison with the nailing hammer for moving said swing beam transversely of the longitudinal axis of said nailing hammer, whereby during alternate downward strokes of said nailing hammer said nailing hammer will first engage said piercing means to drive said piercing means into one of said workpieces and then engage a nail held in the nail-holding sleeve to drive said nail through the said hole and the said workpieces until a portion of the nail shank protrudes from the bottom nost workpiece, and means including a clinching anvil disposed below said table means for engaging and twisting the protruding portion of the nail shank into a spiral and for pressing it against the bottom face of the lowermost workpiece.

5. The device as set forth in claim 4 wherein said nailholding sleeve is provided with blade springs for engaging and supporting a nail therein and for centering the nail with respect to the nailing hammer during the downward stroke thereof against the nail.

6. The device as set forth in claim 4, wherein said table means includes a pivotally mounted plate for supporting the workpieces, and means operable upon the downward strokes of the nailing hammer for pivoting said plate, whereby during at least one of the said downward strokes the protruding shank of the driven nail will be brought into engagement with the clinching anvil.

7. The device as set forth in claim 4, wherein the means operable upon the downward strokes of the nailing hammer for pivoting said plate includes cam means connected to said table means, said cam means being operated by rollers on the suspension means for the nailing hammer. V

8. The device as set forth in claim 4 including a plurality of nailing hammers, a plurality of piercing means, a plurality of nail-holding sleeves, a plurality of clinching anvils, all of said hammers, said piercing means,

said nailing sleeves and said clinching anvils being operatively aligned and common means for operating all of said hammers and clinching anvils in unison.

No references cited. 

